Sparking plug



July 9; 1940; L, 2,207,175

SPARRING PLUG I Filed Feb. 18, 1933 M Patented July 9,

UNITED STATES SPARKING PLUG Ludwig Kral, Vienna, Austria- Application February 18. 1938, Serial No. 191,323 r In Austria February 25, 1937 Claims. 01. 123-169) This invention relates to an improved sparking plug for internal combustion engines especially I for motor vehicles. One object of 'the invention is to improve the sparking eificiency. Spark 5 plugs have to operate under the most varied conditions, namely if the engine is cold or warm or hot. In the case of battery ignition, the ignition tension dropsin accordance with the increasing number of revolutions of the engine while in the event of magneto ignition the said tension increases in accordance with the increasing number of revolutions of the engine. In order to improve the effect of ignition in the case of low tensions, the sparking plugs have been provided with .creeper sparking paths, namely the end of the central electrode projects, to a greater or smaller extent, beyond the surface of the insulator in which the electrode is embedded. The spark develops along said surface and thereafter jumps over the air gap which generally is smaller than in the case of the sparking plugs of known construction. struction the entire sparking distance, consisting .of the creeper" sparking path and the free- 2 sparking gap, can be made" longerthan in the construction in which a freesparking gap only is provided between the two electrodes.

It has been found that, when the tension increases, the spark has the tendency to separate 3 from the "creeper area of the insulator surface and jump in the free space to the electrode of the mass. Now, if as usual, the electrode of the mass is disposed in the plane of the insulator surface,

the raising spark is forced to jump in a,curved 35 path, so that its way is increased and consequently the development of a powerful spark is detrimentally affected:

The present invention is based on the idea to provide for the spark ,the most favorable condi ac tions and it consists in that the mass-electrode ascendingly overlaps the front face of the insulater from its plane towards the axis of the central electrode, so that the spark when it lifts itself away from the creeper. sparking path may form 45 itself in the free sparking gap of different lengths.

Three modes of carryin out the present inven- A tiorrare' illustrated by way of example on the accompanying sheet of drawings in which- Figs. 1 and 2 show a sparking plugin part 50 sectional elevation and in plan view respectively. Figs. 3, 4 and 5, 6 are likeviews of two different constructions .of sparking plugs, I, y

In the constructions shown in Figs. 1 to 4, the

'. central electrode I, mounted in the insulator 2, 55 terminates quite flush with the front face of the It has been found that in this coninsulator, while-in theembodiment illustrated in Figs. 5 and 6 the central electrode i projects slightly beyond the said front face. The masselectrode 3 is mounted in the screw-threaded part 4 of the plug and its face or edge 5, faces the cen- -5 tral electrode and overlaps the front face of the insulator 2. In' the construction shown in Figs. 1 and 2, theface 5 of the mass-electrode 3 is quite straight, starts at least in the height of the plane E-E of the front face and, at its edge, 10 forms a'small free sparking gap. The face or edge 5 of the masselectrode extends towards the .axis X-X of the central electrode and is inclined at an angle of approximately 45 degrees with respect to the plane E-E.

Compared with the construction shown in Figs. 1 and 2, the embodiment illustrated in Figs. 3 and 4 differs in the face or edge 5 of the mass-electrode curved in such a way, that at all of its places it is substantially equally distanced from the end 2 What 1 claimis- '1. A sparking plug, comprising in combination an insulator, a;central electrode mounted in and terminating substantially flush with the front face of saidinsulator, and a mass-electrode arranged outside said insulator and provided with a part slopingly overlapping the front face of said insulator, said-overlapping part of the mass-electrode gradually approaching towards the axis of said central electrode but distancing itself from the front face of said insulator, so that the spark 407 may form itself in the free sparking gap of ,dif-- ferent lengths.

2. A sparking plug, comprising in combination an insulator, a central electrode mounted in and terminating. substantially flush with the front face of said insulator, and amass-electrode arranged outside said insulator and prcvided with apart which faces and overlaps the front face of said insulator and is inclined in a straight line towards the axis of the centralelectrode, so that the spark may form itself in the free sparking gap of different lengths. I

3. A sparking plug, comprising in combination an insulator, a central electrode mounted in and terminating substantially flush with the front face of said insulator, and a mass-electrode arranged outside said insulator and provided with a part which faces and overlaps the front face of said insulator and is inclined at an angle of 45 degrees towards the axis of the central electrode, so that the spark may form itself in the free sparking gap of different lengths.

4. A sparking plug, comprising in combination an insulator, a central electrode mounted in and terminating substantially. flush with the front face of said insulator, and a mass-electrode arranged outside said insulator and provided with a part which faces and overlaps the front face ofsaid insulator and gradually distances itself in a curved path towards the axis of the central electrode, the centre of said curved path beingdisface of said insulator,- and a mass-electrode arranged outside said insulator and provided with an eccentrically curved path which bridges eccentrically said central electrode and said insulator at some distance therefrom, so that the spark may form itself in the free sparking gap of different lengths. I LUDWIG KRAL. 

